Machine for and method of grinding gears, splines, and similar forms



Jan. 5, 1943. w. F. ROSS MACHINE FOR AND METHOD OF GRINDING GEARS,

SPLINES,'AND SIMILAR FORMS 17 Sheets-Sheet 1 Filed Oct. 30, 1939 wk banINVENTOR.

ATTORNEY.

Jan. 5, 1943. w. F. Ross MACHINE FOR AND METHOD OF GRINDING GEARS,

SPLINES, AND SIMILAR FORMS 17 Sheets-Sheet 2 Filed Oct. 30, 1939 Jan. 5,1943. w. F. ROSS MACHINE FOR AND METHOD OF GRINDING GEARS,

SPLINES, AND SIMILAR FORMS Filed 061'. 30, 1939 17 Sheets-Sheet 3 39m a?M.

INVENTOR BY n I A'ILTORNEY.

W. F. ROSS Jan. 5, 1943.

4 t e e h 4 s e e h S S 7 R l A E G MS M m N m m Gml F 0M0 D O m m E O A,d m m Am R n F5 E N I H C A M w. F. ROSS 2,307,238 MACHINE FOR ANDMETHOD OF GRINDING GEARS,

, AND SIMILAR FORMS l7 Sheets-Sheet 5 SPLINES Jan. 5, 1943.

Filed Oct. 30, 1939 INVENTOR.

ATTORNEY.

Jan. 5, 1943. w, oss 2,307,238

MACHINE FOR AND METHOD OF GRINDING GEARS, SPLINES, AND SIMILAR FORMSFiled 001:. 30, 1959 17 Sheets-Sheet 6 INVENTOR.

ATTORNEY.

Jan. 5, 1943. w Ross 2,307,238

MACHINE FOR AND METHOD OF GRINDING GEARS, SPLINEjS, AND SIMILAR FORMSFiled 001',- 50, 1939 17 Sheets-Sheet 7 Jan. 5, 1 w. F. ROSS 2,307,238

MACHINE FOR AND METHOD OF GRINDING GEARS, SPLINES, AND SIMILAR FORMSFiled Oct. 50. 1939 17 Sheets-Shasta 196 24.9 v v 134 I I 137 247 J 24:?166 MMMMMM'E Y.

w j .295 I llllllll llllll-llllll 76 I I 34 I A I V 1943. w. F. ROSS2,307,238

MACHINE FOR AND METHOD OF GRINDING GEARS,

SPLINES, AND SIMILAR FORMS Filed QCt. 30, 1959 17 Sheets-Sheet 9 Jan. 5,1943.

w. F. ROSS 2,307,238 MACHINE FOR AND METHOD OF GRINDING GEARS,

SPLINES, AND SIMILAR FORMS v Filed Oct. 30. 1939 17 Sheets-Sheet 1O ilLl wow $56M.

IN VENTOR.

ATTORNEY.

Jan. 5, 1943.

w. F. ROSS 2,307,233 MACHINE FOR AND METHOD OF GRINDING GEARS, SPLINES,AND SIMILAR FORMS Filed Oct. 50, 1939 17 Sheets-Sheet 11 ATTORNEY.

Jan. 5, 1943. w. F; ROSS 5 3 MACHINE FOR AND METHOD OF GRINDING GEARS,

SPLINES, AND SIMILAR FORMS Filed Oct. 30, 1939 l7 Sheet-Sheet 12 W. F.ROSS Jan. 5, 1943.

D METHOD OF GRINDING GEARS, SPLINES AND SIMILAR FORMS l7 Sheets-Sheet 13MACHINE FOR AN Filed Oct. 30, 1939 Jan. 5, 1943. w. F. Ross 2,307,233

MACHINE FOR AND METHOD OF GRINDING GEARS, v

SPLINES, AND SIMILAR FORMS ATTORNEY.

1943- 'w. F. ROSS 2,307,238

MACHINE FOR AND METHOD OF GRINDING GEARS, SPLINES, AND SIMILAR'FORMSFiled Oct. so, 1939 17 Sheets-Sheet 15 'Jan. 5, 1943. w. F. ROSS MACHINEFOR AND METHOD OF GRINDING GEARS,

SPLINES, AND SIMILAR FORMS 1'7 Sheets-Sheet 16 Filed D612. 30, 1959 d huJan. 5, 1943. v w F, 55 2,307,238

- MACHINE FOR AND METHOD OF GRINDING GEARS,

SPLINES, AND'SIMILAR FORMS Filed oct. 30, 19:59 17 Sheets-Sheet 1'7higher degree of practical without requiring Patented Jan. 5, 19432,307,238 MACHINE FOR AND METRO F GRINDING GEARS, SPLINES, AND :r an B.0

EMS

Walter F. Ross, Detroit, Mich. Application October 30, 1939, Serial No.301,918

Claims.

The object of the present invention is to provide for the finish formingof gear teeth, lobes or similar forms by such means and in such mannerthat gears or forms of great perfection and tooth or formed surfacefidelity both as to contour and spacing may be produced, such gears andforms as a result having a correspondingly strength with noiselessoperation and being capable of production practically withoutrestriction as to tooth or other form. The invention also proposes tosecure relatively high work output at low cost without dependence uponthe skill of the operator and under conditions which will not readilyallow of error on the part of the operator.

Although the invention is not limited in its application to theformation of gear teeth only, it will be hereinafter generally referredto in connection with the finishing of gear teeth only, with theunderstanding that such description also refers by implication to otherforms of teeth. lobes, forms and the like.

It is also an object of the invention, by its means and method ofoperation, to eliminate indexing and the errors common thereto, and toproduce a finished, hardened and ground gear or part in which no lappingis necessary, and in which scaling, shrinkage and distortion of thefinished gear, such as occurs under present methods where hardening isresorted to after the gear has been cut, is corrected and in which atrue concentric pitch circle may be accurately attained.

A further object is to insure, by the means and method of operation ofthe invention, marked evenness of tooth spacing and the finish grindingof a gear or work completely in one setting and the inversion of thegear or work to complete the tooth form as in those grinding methodswherein one side of the tooth is ground at a time. The proposed meansand method are readily applicable to tooth forms of great variety andnumber, and not necessarily restricted to gears as such, being readilyadaptable to the finish forming of splined, cammed, lobed, andinnumerable other such forms. The means and method of the invention willfurther permit the provision of hardened gears for general use wherehitherto, due to manufacturing difliculties which are by this inventionovercome, soft gears have been used in the interest of accuracy but atthe expense of durability.

It is also an object of the invention to obviate the high expense andnecessity of ground hobs and tooth-shaving machines such as are atpresto provide novel ent used to secure accuracy and eliminate cuttermarks, distortions and errors resulting from intermediate gear cuttingoperations such as are now commonly resorted to.

An important object of the said invention is to provide a main grindingwheel having a thread formed thereon in such a manner that the sectionof the wheel face taken normal to the helix is the conjugate of thenormal pitch of the gear 10 being ground and which is accurate andspecifically adapted to the contour of each specific size, style, andspace of tooth; and which is further adapted to progressively grind thefull form of each tooth simultaneously on both sides around 15 the gearin continuous cutting relation thereto,

without the indexing which is usually called for.

A further important object is to provide for the reduced reproduction ofan enlarged pattern of the required conjugate rack tooth space sectionby steps which include the dressing of the said form of tooth section bypantograph control on a dresser wheel, and the recessing of such form bysaid dresser wheel in the surface of the grinding wheel as a helixhaving the normal pitch of the normal pitch of the teeth to be ground inthe work. The invention also contemplates formation of such helicalgrinding wheel with a face width of some whole multiple of the helixlead as a means of insuring running 0 balance.

Still further, it is an important object of the invention to provide forcontrol of rotation of the gear through a plurality of differentialgears so interrelated that the speed of gear rotation may be readilyadapted to a variety of numbers of .teeth far in excess of thatfor whichordinary feed change gear combinations are usually adaptable.

The invention also contemplates combination 40 of such interrelateddifferentials with means controlling the motion of the gear for thegrinding of helical teeth, and for the grinding of taper teeth andspecial forms.

A still further object of the said invention is means for theelimination of torque flutter in the transmission of power to the work.

Still further objects or advantages subsidiary to resulting from theaforesaid objects, or from the construction or operation of theinvention as it may be carried into effect, will become apparent as thesaid invention is hereinafter further disclosed.

In carrying the said invention into effect, I

5 may provide a gear or form grinding machine comprising, in general, alarge rectangular base structure having mounted on the center portion amain grinding wheel characterized by its being provided with a helicalthread of a cross section at right angles to the lead thereof which isthe conjugate rack of the normal pitch of the gear to be ground; and inadvance of said grinding wheel a dresser wheel driven by a small motormounted for adjustment to angular positions about a horizontal axis atright angles through the axis of rotation of the dresser wheel, wherebysaid dresser wheel may be set at an angle equivalent to the helix angleto be dressed on the main grinding wheel.

Suitable mechanism is provided to effect the movement of the dressingwheel in a direction parallel to the axis of the main grinding wheel toadjustable limits in either direction, and to effect its movement intoand out of working position relative to the said main grinding wheel atopposite ends of its working travel, much in the manner of the action ofa threading tool when used in a lathe. Means for progressively feedingthe dresser wheel into the grinding wheel to promote the dressing outare also providecl.

For the formation of therequired contour of the margin of the dressingwheel in order that it may produce the proper helix section on the maingrinding wheel, I may provide on the forward end of the machine apantograph mechanism adapted to translate the template-controlled motionof a tracer disc into reduced motion of adressing diamond which may bemoved up to the aforementioned dresser Wheel to efiect its dressing, thediamond being accurately lapped and polished, in so far as itsactiveedge is concerned, to a circular cross section whose diameter is afraction, (say, one-tenth) of that of the tracer disc. A template havingthe form of the rack tooth space to be ground by the main grindingwheel, and in the same proportion thereto as the tracer disc is to thediamond say, times the section) is suitably mounted on the machine forguidance of the tracer disc during the operation of dressing the dresserwheel by the said diamond.

On the rear part of the machine, I propose to mount the work handlingmechanism which may be in the form of a trunnion carrying the work tablemounted for rotation in a plane transverse of the machine to permit thegrinding of helical gears of any lead angle, feed change gear controlbeing provided to control traverse of the work table in the direction ofits length and high speed reverse operation of the said work table whenits working stroke is completed. The gears to be ground may be mountedeither singly or in groups on suitable arbors carried between aheadstock and tailstock on the work table, these arbors being equippedwith special dogs adjustable to secure a definite rotary position of thework in reference to the tooth space of the gears to insure properregister at all times with the helical form on the grinding wheel.

The grinding wheel and the work are coupled for operation insynchronized unison from a common source of power and the work rotatingmechanism may and preferably includes a main differential, thepinion-carrying section of which is under the control of an auxiliarydifferential. From a main constant-speedshaft power is directed throughchange speed gears to produce rotation of the work around its own axis,and also directed through other change speed gears to produce thedesired feed motion and rapid return of the table.

For the grinding of helical gears I propose to bring into operation afurther change gear train which causes the work spindle to lose or gainone revolution in a work travel distance equal to the helix lead, saidlast mentioned gear train deriving its operating force from the movementof the work table; and to adapt the machine to the grinding of taperforms, such as milling cutters, taper spline shafts and gear generatingcutters, I may provide further gearing also coupled to the work tablefeed to advance the work towards the main grinding wheel as it traversesthe same.

Since accuracy in grinding is of prime importance and the transmissionof power through shafting and gearing may result in a certain torqueflutter, I propose to incorporate in the machine an adjustable pressurebrake as close to the working end of the said work spindle as possible,and means for adequately lubricating and cooling the said brake.

All of which is more particularly described and ascertained hereinafter,by way of an example, having reference to the accompanying drawings,herein:

Figure 1 is a front end elevation of a machine embodying said invention:

Figure 2 is a side elevation of the major front portion of the same:

Figure 3 is a plan of the same;

Figure 3A is a diagram illustrating the pantograph linkage associatedwith the form template;

Figure 4 is a side elevation of the major rear picrtion of the machinelooking at the left hand 5 e;

Figure 5 is a side elevation of the right side of the transmissionhousing of the machine;

Figure 6 is a transverse section through the trunnion head of themachine taken on a plane indicated by'the line B6, in Figure 7;

Figure 7 is a vertical section of the trunnion head of the machine takenthrough the axis thereof;

Figure 8 is a similar vertical section oi the transmission casing of themachine;

Figure 9 is a plan of the trunnion head, partly broken away and insection;

Figure 10 is a plan of the transmission casing with the cover platepartly broken away to disclose the internal mechanism;

Figure 11 is a transverse section of the transmission casing taken on aplane indicated by the line illl, in Figure 10;

Figure 12 is a similar section taken on a plane indicated by the line I2l 2, in Figure 10;

Figure 13 is a horizontal detail section of the selective gear traintaken on a plane indicated by the line I 3i 3, in Figure 4;

Figure 14 is a vertical section of the headstock and adjacent parts ofthe work table;

Figure 15 is a partial plan of the said headstock;

Figure 16 is a vertical section of the forward part of the machine takenon a plane indicated by the line iii-l6, in Figure 3;

Figure 17 is a horizontal section of the forward end of the basestructure taken on a plane indicated by the line l1il, in Figure 16;

Figure 17A is a detail sectional view illustrating the adjustablemounting of the dresser wheel feed screw;

Figure 18 is a. horizontal section taken on a 2&07338 plane indicated bythe line iii-i8, in Figure 16;

Figure 19 is a detail plan of the worn, grindin wheel and dresser wheelshowing their relation one to the other.

Similar characters of reiierence indicate similar parts in the severalfigures of the drawings. Gertain supporting structure which wouldinteriere with a clear illustration of the mechanism and which is notnecessary to an understanding thereof is eliminated from some of thesectional illustrations of the drawings.

The machine, as illustrated, has a substantially rectangular basestructure 213 with chambers 2i and 22 extending laterally from its forrdportion, the chamber iii enclosing part of the dresser feed mechanism tobe later described, and the chamber 22 merely a reservoir for coolantwhich is pumped therefrom by the motor 28 to such parts of the machineas may be required in accordance with common practice.

Intermediate oi the length of the machine is the main grinding wheel 25,the spindle 25 of which is rotatively carried by a slide 26 parallelthereto and adjustable transversely of the ma chine in ways El by amanual feed screw 28.

Positioned on the machine in advance of the main grinding wheel 2% is adresser wheel 29 mounted on the spindle 8b of a motor 8|, which motor iscarried by an arcuate member $32 for swinging movement about the centerof the dresser wheel 29 by virtue of its beingrotatable in arcuate ways88 of a quadrant support 34. Also carried by the motor support member 32is a pantograph tablets, movable on the said member 32 from one dresserwheel 29 by means of the manually operable adjusting shaft 36 throughthe medium of gears 37 and 38 and of the feed screw 39.

The quadrant support it and the previously described elements mountedthereon is movable longitudinally and transversely of the machine byreason of its being in turn provided with a saddle t adjustablelengthwise of the machine on a slide member :32 by means or the manualadjusting screw fill. The slide member 52 is also carried by a saddle ddtransversely moveable of the machine on the cross slide dd under theinfluence of a feed screw 45 engaging in a nut 55 on the underside ofthe said saddle t3, the means of operating the said feed screw 65 beinglater referred to. The slide dd is also capable of reciprocation in thedirection of the length of the machine by virtue of its being mounted ona longitudinally slidable member t! which receives its motion from apinion B8 engaging a rack 89 on the underside of the said member 61, thesource of operation of the pinion 48 being also referred to in detailhereinafter.

From the foregoing arrangement of slides it will be seen that provisionis made whereby the dresser wheel 29 and the main grinding wheel 24 aremovable relatively to each other in practically all directions, and inthe illustrated example all of these adjustments and movements are forconvenience associated with the said dresser wheel 29, the main grindingwheel 2% in this case being non-adjustably mounted on the machine exceptinsofar as the manual cross feed by the said screw 28 is concerned. Thiscross feed of the main grinding wheel 24 does not.

however, have any bearing on the relationship The main grinding wheel 2%is intended to be driven at a high speed in one direction whenperforming its gear grinding operation and receiving its power from themain motor 60, but when the thread is being formed on the main grindingwheel 25 by the dresser wheel 29 it is driven in alternately changingdirections at low speed, receiving its power from a smaller auxiliarymotor 5i which is shown in this case as being situated outside of theextension 2! of the base structure of the machine; the selection of thedrive to the main grinding wheel being controlled by a menually operatedclutch according to requirements. When the main grinding wheel 26 isbeing driven for the grinding of work, it receives its power from themain motor 56 through the medium of a Reeves gear 62, main pulley t3,belt ht, pulley t5, clutch member as which rotates with the shaft 57 andis moved into engagement with through the pulley es and belt to to thelarge pulley at of the grinding wheel spindle 25.

62 is the Reeves gear control hand wheel which, through the shafts S3,66, and 89, sultably geared together, controls the regulation of thesaid Reeves gear, in the manner well known. to increase or diminish thespeed of the main grinding wheel within reasonable limitations to suitvarying degrees of wheel hardness or abrasive quality, or to meet othervariable grinding conditions, such as differing gear hardness, and soforth.

Nominally it is proposed to proportion the pulleys and the motor speedto provide a countershai't speed of 3600 R. P. M. and a grinding wheelspindle speed of 1800 R. P. M. grinding wheel spindle speed, beyond thatpermitted by regulation of the Reeves gear, being simply efiected byvarying relative sizes of the pulleys 59 and 6!.

Continued description of the mechanism of the machine and its operationwill be confined to that actually involved in the grinding of gears forthe present, and the method of preparing the grinding wheel for its workwill be thereafter described.

Approximately the entire rear half of the machine is confined to themechanism for carrying and moving the work relative to the grindingwheel 25, the said main grinding wheel 25 being in this examplenon-adjustable as to position ing member Tl on the underside of thetrunnion head it and passing over a sprocket "it carried by the saidsub-saddle it.

The said sub-saddle it, carrying the trunnion head it and transmissioncasing H and the parts which they support, is also capable of movementlongitudinally of the machine by the coarse adjustment feed wheel isthrough the medium of the cross shaft 80, worm and worm wheel 8i and 82and the pinion 83, which pinion engages a

